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MCQ on Electrical Technology

1. The reciprocal of permeability is known as-

(a) Conductivity

(b) Reluctance

(c) M.m.f

(d) None of this

Ans:b

2. Kirchhoff’s laws are valid for

(a) Dc circuit only

(b) Ac circuit only

(c) Both dc and ac

(d) None

Ans: c

3. The unit of magneto motive force is

(a) Maxwell

(b) Amp-turn

(c) Weber

(d) Mho

Ans: b

4. The form factor for a sinusoidal ac voltage is

(a) 1.41

(b) 1.11

(c) 1.00

(d) 0.707

Ans: b

5. The equivalent resistance of two resistance A & B(A<B) in parallel will be

(a) Greater than A

(b) Greater than B

(c) In between A and B

(d) Less than A

Ans: d

6. The frequency of an ac voltage given by e=100sin314t is

(a) 50Hz

(b) 314Hz

(c) 60Hz

(d) None

Ans: a

7. The strength of an electromagnet depends upon

(a) Voltage and size of the wire

(b) The current and the size of the wire

(c) The voltage and number of turns

(d) Current and number of turns


Ans: d

8. If the rated voltage V and rated wattage W are known to us, then the resistance R of the material can

found from the following

(a) 𝑊

𝑉

(b) 𝑉2

𝑊

(c) 𝑊2

𝑉2

(d) 𝑁𝑜𝑛𝑒

Ans: b

9. When two resistance R1 and R2 are connected in parallel then the total resistance will be

(a) 𝑅1𝑅2

𝑅1+𝑅2

(b) 𝑅1+𝑅2

𝑅1𝑅2

(c) 𝑅1

𝑅1+𝑅2

(d) 𝑅2

𝑅1+𝑅2

Ans: b

10. If the temperature is increase to a semi conductor then resistance will

(a) Decrease

(b) Increase uniformly

(c) Increase irregularly

(d) None

Ans: a

11. An active network is one which contains

(a) No source of emf

(b) At least two source of emf

(c) One or more than one source of emf

(d) None

Ans: c

12. Kirchhoff’s 2nd law relates to

(a) Current

(b) Resistance

(c) Voltage

(d) None

Ans: c

13. 40 no. of resistance of 40Ω each are connected in parallel, then the equivalent resistance will be

(a) 2000Ω

(b) 1600Ω

(c) 1Ω

(d) 80Ω

Ans: c

14. The resistance of 10Ω each is connected in star connection. The equivalent delta will have the resistance

(a) 30Ω

(b) 45Ω


(c) 25Ω

(d) 5Ω

Ans: a

15. The supply voltage of domestic installation represents

(a) Average value

(b) Rms value

(c) Maximum value

(d) None

Ans: b

16. Kirchhoff’s law are valid for

(a) Dc circuit only

(b) Ac circuit only

(c) Both dc and ac circuit

(d) None

Ans: c

17. If the voltage of a circuit is reduced to half and the resistance is doubled, the current becomes

(a) Four times

(b) Double

(c) One fourth

(d) Half

Ans: c

18. The power loss in electrical circuit can take place in

(a) Inductance only

(b) Capacitance only

(c) Resistance only

(d) All of above

Ans: c

19. the reciprocal of resistance is known as

(a) Admittance

(b) Conductance

(c) Susceptance

(d) None

Ans: b

20. Two capacitor of capacitance C1 and C2 are connected in series. The equivalent capacitance will be

(a) 𝐶1𝐶2

𝐶1 +𝐶2

(b) 𝐶1 + 𝐶2

(c) 1

𝐶1+𝐶2

(d) 𝐶1+𝐶2

𝐶1𝐶2

Ans: a

21. An alternating current generator having 4 poles and running at a constant speed of 600rpm producing an

alternating voltage having of frequency of

(a) 50Hz

(b) 100Hz


(c) 1000Hz

(d) 20Hz

Ans: a

22. Three resistances each of RΩ are connected to form a triangle. The resistance between any two terminal

will be

(a) RΩ

(b) 3

2𝑅Ω

(c) 3𝑅Ω

(d) 2

3𝑅Ω

𝐴𝑛𝑠: d

23. When sinusoidal voltage is applied across a pure capacitor, the current in the capacitor

(a) Lags the voltage by 900

(b) Leads the voltage by 900

(c) Is in phase with applied voltage

(d) None

Ans: b

24. The peak factor of a sine wave is

(a) 1.11

(b) 1.414

(c) 2

(d) 1.5

Ans:b

25. The property of material which opposes the creation of magnetic flux in it ,is called

(a) Permeability

(b) Intensity

(c) Magnetizing force

(d) Reluctance

Ans: d

26. The unit of flux density is

(a) Tesla

(b) 𝐴𝑇

𝑚2

(c) 𝑊𝐵

𝑚2

(d) 𝑛𝑜𝑛𝑒

Ans: c

27. The energy stored in a magnetic field is given by (L=self inductance, I=current)

(a) L2I

(b) 1

2𝐿𝐼2

(c) 1

2𝐿𝐼

(d) 1

2𝐿2𝐼

Ans: b

28. The Megger is used to measure

(a) Current


(b) Electric energy

(c) Insulation resistance

(d) Low resistance

Ans: c

29. Wattmeter is used to measure

(a) Current

(b) Resistance

(c) Power

(d) Voltage

Ans: c

30. An alternating current is given by i=10sin314t. the time taken by the current to reach a value of 10A is

(a) 0.025sec

(b) 0.05sec

(c) 0.01sec

(d) 0.02sec

Ans: c

31. A wire is stretched to its double the length ,the new resistance will be

(a) 4 time the original resistance

(b) Double the original resistance

(c) Half the original resistance

(d) One-fourth the original resistance

Ans:a

32. When the frequency of supply voltage is increased the resistance of an inductor will

(a) Increase

(b) Decrease

(c) Remain same

(d) None

Ans:c

33. The ability of the material to set-up a magnetic field is called

(a) Permittivity

(b) Permeability

(c) Retentivity

(d) None

Ans:b

34. Capacity of battery is indicated by

(a) Ampere

(b) Volt-ampere

(c) Ampere-hour

(d) Watt

Ans:c

35. In a d.c. machine brushes are made of

(a) Carbon

(b) Graphite

(c) Copper


(d) None

Ans:a

36. If the field of a d.c. shunt motor running without load get opened then the motor will

(a) Stop

(b) Slow down

(c) Run normally

(d) Pick-up high speed

Ans:d

37. The specific gravity of the electrolyte of an lead acid battery gives an indication of

(a) The change of the battery

(b) The emf of the battery

(c) Level of electrolyte

(d) Damage caused to the plate

Ans:a

38. The material can be used for a permanent magnet is

(a) Alloy steel

(b) Soft iron

(c) Cast-iron

(d) Any of the above

Ans:a

39. D.c. series motor are best suited for electric traction as it

(a) Delivers High starting torque

(b) Runs at very high speed

(c) Cheaper in cost

(d) Consumes less power

Ans:a

40. The maximum value of sine wave current is 100 amps , the rms value of current is

(a) 7.07 amps

(b) 66.37 amps

(c) 70.72 amps

(d) 90 amps

Ans:c

41. The power factor of a circuit is 0.9 , the Q-factor will be

(a) 0.111

(b) 1

(c) 1.111

(d) None

Ans: c

42. The insulation resistance of a 240V wiring installation should not be less than

(a) 5MΩ

(b) 2MΩ

(c) 1MΩ

(d) 0.5MΩ

Ans: c


43. An ammeter can be used as voltmeter by using with it

(a) Shunt of high resistance

(b) Series of high resistance

(c) Shunt of low resistance

(d) Series of low resistance

Ans: b

44. In a circuit containing R,L and C, power loss takes place in

(a) L only

(b) C only

(c) R only

(d) All of above

Ans: c

45. Power factor of electric incandescent lamp is

(a) Lagging

(b) Unity

(c) Leading

(d) Zero

Ans: b

46. Full safety of an electrical installation is ensured when it is provided with

(a) Proper insulation

(b) Good earthing

(c) Proper fuse in circuit

(d) All of above

Ans: d

47. To start a dc shunt motor below the rated speed, a resistance is inserted in series with

(a) Motor

(b) Armature

(c) Field winding

(d) Any of the above

Ans: b

48. For transmission over a long distance, high voltage is preferred because

(a) It requires conductor of less cross section area

(b) Copper loss is less

(c) Voltage regulation is better

(d) All of the above

Ans: d

49. Meter constant of an energy meter is expressed in the form of

(a) Number of revolutions/kW

(b) Number of revolutions/minute

(c) Number of revolutions/kWh

(d) kWh/revolution

Ans: c

50. The range of an ammeter can be increased by connecting with it

(a) A low resistance with series


(b) A high resistance with series

(c) A low resistance in parallel

(d) A high resistance in parallel

Ans: c

51. The voltage of 1000W heater is reduced to half, the output will be reduced to

(a) 500W

(b) 250W

(c) 125W

(d) Same

Ans: b

52. A lead acid storage battery rated at 120Ah will deliver a current of 5A for approximately

(a) 24hrs

(b) 12hrs

(c) 5hrs

(d) 120hrs

Ans: a

53. A 1100/400V single phase transformer has 100 turn on the secondary the number of primary turn is

(a) 550

(b) 275

(c) 1100

(d) None

Ans:b

54. In a series R-L circuit the applied voltage

(a) Lags the current

(b) Leads the current

(c) Is in phase with voltage

(d) Lag by 900

Ans:b

55. The d.c. motor used in railway traction is

(a) Shunt motor

(b) Series motor

(c) Compound motor

(d) Any of them

Ans:b

56. If d.c. series motor is started without load the motor will

(a) Not take start

(b) Run slowly

(c) Run at normal speed

(d) Pick-up high speed

Ans:d

57. If an ammeter is connected in parallel with the load ,it will

(a) Indicate low the reading

(b) Burn out


(c) Indicate zero reading

(d) None

Ans:b

58. The moving iron voltmeter can be used

(a) Both a.c. and d.c.

(b) A.c only

(c) D.c. only

(d) None

Ans:a

59. P.M.M.C. type volt-meter can be used in

(a) A.C. circuit only

(b) D.C. circuit only

(c) Both a.c. and d.c.

(d) None

Ans:b

60. Rating of a transformer is expressed in

(a) KW

(b) KVA

(c) KVAR

(d) None

Ans:b

61. From heating point of view Id.c is equal to

(a) Imax value

(b) Ir.m.s value

(c) Iaverage value

(d) None

Ans:b

62. Power factor of an ac circuit is ratio of the resistance to the

(a) Inductive reactance

(b) Capacitance reactance

(c) Impedance

(d) None

Ans:c

63. In a R-L-C series circuit ,if inductive reactance is grater then the capacitive reactance then the power

factor is said to be

(a) Unity

(b) Lagging

(c) Leading

(d) None

Ans:b

64. A coil of resistance 6Ω and inductive reactance is 8Ω ,then the impedance of the coil is

(a) 14Ω

(b) 2Ω

(c) 10Ω


(d) None

Ans:c

65. The component of current which is quadrature with supply voltage is said to be

(a) Active component of current

(b) Watt-full component of current

(c) Watt-less component of current

(d) None

Ans:c

66. In a purely inductive a.c. circuit

(a) The circuit current leads the voltage by 900

(b) The circuit current is in phase with the voltage

(c) The circuit current lags the voltage by 900

(d) None

Ans:c

67. The impedance of the coil having a resistance of 20Ω and an inductance of 0.02H are connected is series

to an 240volt ,50Hz a.c. supply is

(a) 20Ω

(b) 20.96Ω

(c) 15Ω

(d) 22Ω

Ans:b

68. In an a.c. system the ratio of the maximum current and R.M.S current is called

(a) From factor

(b) Peak factor

(c) Load factor

(d) None

Ans:b

69. The core of the transformer is made of

(a) Aluminium

(b) Galvanized iron

(c) Silicon steel

(d) None

Ans:c

70. Ten number of 2 volt cells are connected in parallel manner then the output voltage will be

(a) 20volt

(b) 5 volt

(c) 2 volt

(d) None

Ans:c

71. The commutator of d.c. generator

(a) Reverse the direction of the current in the armature

(b) Changes a.c. to the d.c. within armature

(c) Keeps the current in one direction in the load

(d) Act as a sliding electrical contact


Ans:b

72. Laminations of core are generally made of (a) Case iron (b) Carbon (c) Silicon steel (d) Stainless steel Ans: c

73. The armature of D.C. generator is laminated to (a) Reduce the bulk (b) Provide the bulk (c) Insulate the core (d) Reduce eddy current loss Ans: d

74. Capacitors for power factor correction are rated in (a) kW (b) kVA (c) kV (d) kVAR Ans: d

75. Pure inductive circuit (a) Consumes some power on average (b) Does not take power at all from a line (c) Takes power from the line during some part of the cycle and then returns back to it during other part of the cycle (d) None of the above Ans: c

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